Toilets generally include a water closet and a flush valve that rapidly empties most of the water from the closet into the toilet bowl to flush it. The flush valve generally includes a toilet flush fitting that is fixed in place and forms a valve seat, and a valve member that pivots up off the seat for flushing and which then moves down against the seat to seal it. The fitting also includes a tall overflow tube that extends above the level of water in the closet, and which passes a moderate amount of water immediately after each flushing to refill the toilet bowl.
Two types of toilet flush fittings are commonly found in homes. A newer type that is molded of plastic and which comprises about 60% of fittings currently in use, includes a pair of posts projecting from the base of the overflow tube to pivotally support a valve member. An older type of fitting which is generally of brass and comprises about 40% of those currently in use, does not have any mounting posts. Two general types of replacement valve members are commonly sold. One type includes a rigid plastic frame with an elastomeric sealing member. Another type is made entirely of elastomeric material and forms its own "living" hinge.
Valve members made entirely of elastomeric material have a relatively short life such as a couple of years, because the soft rubber or soft vinyl absorbs chemicals in the water supply and tends to swell. The swelling can change the length of the flapper, which moves its valve closing surface away from the valve seat and which also warps its closing surface, so a good seal is not achieved. A simple and low cost valve member assembly which could be mounted on either type of common toilet flush fitting (with or without mounting posts), which provided a rigid plastic yoke to pivotally support the tank ball, and which could be easily and reliably installed, would be of considerable value.
Some types of replacement flush valves include a valve seat member that fits over the existing valve seat, to replace a corroded or worn valve seat. Such a valve also includes a pivoting valve member, which can be of the same construction as the type of valve member meant to pivotally mount on the refill tube. Where the water closet is of low capacity such as 3.5 gallons, insufficient water may be dispensed to achieve complete flushing, and double flushing may be required. Double flushing can often be avoided by attaching a delay cup to the valve member, which delays closing of the flush valve so more water from the water closet is dispensed in each flush cycle. However, it is often desirable to allow adjustment of the delay cup so not too much nor too little water is dispensed in each cycle, to save water while achieving complete flushing. U.S. Pat. No. 4,907,302 shows a valve member with stops of variable sizes that limit the angle by which a valve member with a delay cup can pivot, with the stops being easily cut away to control the amount of water dispensed in each cycle. Apparatus which enabled fine adjustment of the amount of dispensed water and which was easier to adjust, would be of considerable value.
Replacement valve members of the type that include a soft rubber tank ball mounted on a rigid plastic yoke, can assure long, reliable closing against an existing flush valve seat. However, valve seats lie at slightly different heights relative to the joints that pivotally support valve members, and some valve seats are tilted slightly. A low cost valve member which had a tank ball that could seal against such seats of variable height and tilt would be of considerable value.